Low-Profile Periscopes Sharpen the View

EuroPhotonicsJul 2008
LONDON -- The Royal Navy’s Astute-class submarines will be equipped with nonhull-penetrating periscopes from Thales UK, based in Addlestone. The electro-optic systems will enable greater flexibility in the design of the submarines and will provide operators with an improved view of the surface without revealing their vessel’s position. The optronic masts will be powered by the VxWorks real-time operating systems, which are produced by Wind River Inc. of Alameda, Calif., USA.

Next-generation Royal Navy submarines could sport a nonhull-penetrating periscope, which is designed to inspect the ocean surface without revealing the position of the vessel.The next-generation submarines, which will be designed to patrol the seas worldwide, would be particularly vulnerable to detection by surface ships when their periscope is raised to assess a situation on the surface. The nonhull-penetrating design of the masts reduces this risk. It enables the sensor head unit to be extended from the submarine fin, where it can rapidly perform a 360° scan above the surface. The image data would be analysed by submarine personnel afterward to minimize the risk of detection.

The masts will use the VxWorks operating systems — running on Thales’ quad PowerPC AltiVec commercial off-the-shelf boards and the AdaCore GNAT Pro software — to power the stabilization system (three-axis to subpixel accuracies), the video and thermal camera control, the communication with the in-hull systems, and the control of the mechanisms and motors in the sensor head unit. The latter is an electro-optical assembly that contains cameras, optics, environmental sensors and stabilization mechanisms. It is designed to function in temperatures ranging from –15 to 60 °C and to withstand a nearby blast.

Inside the hull, the mast control unit coordinates system activity and communicates with the submarine’s tactical, data and combat systems. Using two processors running on VxWorks, it controls the mast-raising equipment and the azimuth drive module. The module rotates the sensor head unit and forms part of the stabilization system, which requires high-performance servo control to compensate for the boat’s movement and to provide the desired clear image for an effective inspection.